JPS60195111A - High-fluidity impact-resistant polypropylene resin composition - Google Patents

Abstract

PURPOSE:To provide the titled composition of good balance between rigidity and impact resistance with high elongation at break, having both specific melt flow index (MFI) and molecular weight distribution. CONSTITUTION:The objective composition can be obtained by (co)polymerization using a stereoregular catalyst [e.g. (C2H5)2 AlCl-TiCl3], of either propylene singly or propylene with a small amount of ethylene followed by, pref. in the same system, reaction between ethylene and propylene so that the weight ratio of the ethylene to the propylene falls between 20/80 and 95/5. The resulting composition has the following characteristics: (1) MFI >=20; (2) kerosene-soluble (at 30 deg.C) fraction (A) accounts for 5-20wt%; (3) ethylene content of the fraction (A) 20- 70wt%; (4) kerosene-insoluble (at 30 deg.C) and boiling n-heptane-insoluble fraction (B) accounts for 50-90wt%; (5) MW/MN values for both the fractions (A) and (B) >=5.0, respectively. This ratio is calculated by the following procedures: said fractions (A) and (B) are each subjected to gel permeation chromatography (GPC) to determine molecular weight distribution curve, the high-molecular weight region of which is approximated with Gaussian distribution.

Description

[Detailed Description of the Invention] +5J IIF Eye Juice J Il+ kFen-no・74 Kazutsuji81~L Impact-resistant polypropylene resin for injection molding with high fluidity and large elongation at break Regarding the composition.

Polynolopyrene is a lightweight, highly rigid, and inexpensive resin that is used for many purposes, especially 71? Block copolymers with ethylene have improved impact resistance, which is a drawback of lipropylene, and have a good balance between rigidity and side impact resistance, and are used in many applications, especially as resins for injection molding. On the other hand, due to recent demands for saving resources and energy, it has become important to improve fluidity during molding and to reduce the thickness of molded products.

In order to improve the fluidity during molding, the molecular weight of the resin is reduced. However, when the molecular weight of the resin is lowered, there is a problem in that the elongation at break, which correlates with the practical impact resistance of the molded product, decreases significantly.

An object of the present invention is to provide a highly fluid I-lipropylene resin composition that has a good balance of physical properties between rigidity and impact resistance and has a high elongation at break.

The present invention has a melt flow index (MFI) of
The part (A) that is soluble in white kerosene at 30°C above 0 is 5% of the total.
or 20% by weight, and the ethylene content in the core is 20~20% by weight.
70% by weight, and the part (B) which is insoluble in white kerosene at 30°C and insoluble in boiling n-hebutane accounts for 50 to 90% by weight of the total, and parts (4) and (B). The high molecular weight range, low molecular weight range, and intermediate weight range are centered on the peak position of the molecular weight distribution curve measured by rubble permeation chromatography (GPC) and the vertical axis is the elution amount and the horizontal axis is the natural logarithm of the molecular weight. Highly fluid polyzolopyrene with high elongation at break, characterized in that MW/MN of parts (4) and (B) are each 5.0 or more when the high molecular weight region is approximated by a Gaussian distribution. The present invention relates to a resin composition.

In this study, the melt flow index (■゛engineering) was determined according to ASTM D1238 at 230℃ and a load of 2.16kg.
Measured according to the method of -62T. (2) When I is less than 20, when a thin injection molded product is manufactured, flow irregularities occur and the surface of the molded product is not uniform, which is undesirable.

In the present invention, GPC is measured at 135°C using 1,2,4-trichlorobenzene as a medium. The molecular weight was calculated using the standard molecular weight of polystyrene, and 0.639 (Q factor of polypropylene/Q factor of polystyrene) was used as the Q factor ratio. Further, the calculation was made assuming that a copolymer of ethylene and propylene also has the same refractive index and Q factor value as polypropylene.

My/M N in the present invention is calculated as follows; as shown in Figure 1, the horizontal axis is expressed as the natural logarithm of the molecular weight, and the vertical axis is expressed as the elution amount. The molecular weight distribution curve on the polymer side is approximated to a Gaussian distribution.

For example, the method of approximating the molecular weight distribution with a Gaussian distribution is
rnal of chromatographic 5
science, vo120+June 1982, 25
2 is explained in detail. That is, the molecular weight distribution curve is approximated by the following formula.

Y = Ym -exp (-(X-Xm)2/2S2
) Y: Height when natural logarithm of molecular weight (tn (molecular weight)) The peak height calculated as follows.

S=tn (weight average molecular weight/number average molecular weight), weight average molecular weight/number average molecular weight, ie, Mw/Ms is calculated.

In the present invention, separation of the portion (6) soluble in white kerosene at 30° C. is carried out as follows. The resin composition is dissolved in white kerosene at 130°C, then the temperature is slowly lowered to 30°C over 3 hours, maintained at 30°C for 12 hours, and then filtered to separate it from the non-bathed portion.

The insoluble part is washed repeatedly with kerosene, and the cleaning liquid is used as a soluble part together with the p liquid. The washed insoluble portion is further washed with n-hebutane (11) and then sieved and further extracted with boiling 114.n-hebutane for 6 hours using a Soxhlet extractor to obtain an extracted residue.

The core is designated as (B).

In this investigation, the portion soluble in white kerosene at 30°C (
4) must be 5 to 20% by weight of the whole, and if it is less than 5% by weight, the impact resistance will be insufficient (if it is more than 20% by weight, the rigidity will be poor.If the ethylene content of the core is 20% by weight) %
If it is less than 70% by weight, the impact resistance will be poor, and if it is more than 70% by weight, the surface gloss will be poor when it is made into a molded product, which is not preferable. Preferably, the resolution is 25cm to 60cm.

In the present invention, the above-mentioned portion (B) which is insoluble in white kerosene at 30°C and insoluble in boiling n-hezotane must account for 50 to 90% by weight of the whole, and if it is less than 50% by weight, the rigidity is poor and 90% by weight. If it exceeds %, the impact resistance will be poor.

What is important in the present invention is that the MW/MN of parts (4) and (B) as measured by the method described above is 5.0 or more, particularly preferably 5.5 or more. Even if the overall MW/MH of parts (A) and (B1) is large, if the MW/MN in the high molecular weight range is less than 5.0, the effects of the present invention cannot be achieved, and conversely, the overall MW/MN is Even if it is small, if Myy/MN in the high molecular weight range is 5.0 or more, the elongation at break will be large.

There are no particular limitations on the method for producing the resin composition of the present invention, and there may be a multi-stage polymerization method in which the reaction ratio of nolopyrene and ethylene is changed in an appropriately designed polymerization method, or a method using part (4) and (
There is a method of kneading both parts so that part B has the above-specified composition ratio, but it is preferable to first polymerize zolopyrene alone or in a small amount using a known stereoregular catalyst in the same polymerization system. In this method, a block copolymer is obtained by carrying out ethylene copolymerization, and then carrying out a reaction such that the reaction ratio of ethylene and zolopyrene is 20/80 to 9515 by weight.

Even if the same reaction is carried out depending on the catalyst used, the proportions of the above parts (A) and (B) will be different, and the MW/MN will also be different, so the proportions of the above parts (4) and (B) will be different. It is necessary to specify conditions for the catalyst to be used in which the ethylene content of part (4) is 5 to 20% by weight and 50 to 90% by weight, respectively, and the ethylene content of part (4) is 20 to 70% by weight.

In some cases, it is also possible to increase the MFI by heating and mixing the obtained copolymer with a peroxide and thermally degrading it, but if thermally degrading, the Mw/MN becomes smaller, resulting in thermal deterioration. The block copolymer used must have a considerably large MW/MN.

In order to make the Mw/MN of the high molecular weight range of parts (4) and (B), which are important in the present invention, to be 50 or more, the usual polymerization conditions are used, that is, the hydrogen concentration in the gas phase is constant and the temperature is constant. Measure the molecular weight distribution of the copolymer obtained by polymerization, divide the molecular curve into three parts using the method described above, find the molecular weight at the boundary point of high molecular weight (II+), and find the molecular weight that has a peak in a molecular weight range larger than that molecular weight. Polymerization conditions are set to obtain a copolymer with a molecular weight that shows a distribution curve.Usually, the hydrogen concentration in the gas phase and the polymerization temperature may be set.

The two conditions determined in this way are hydrogen concentration and temperature (in the case of Shinta, conditions for obtaining a copolymer with an even higher molecular weight are added)
A desired copolymer can be obtained by carrying out the following in the same polymerization system.

A more preferable method is to obtain a block copolymer by dividing the initial step of polymerizing noropylene alone or copolymerizing it with a small amount of ethylene into two steps in which the hydrogen concentration is changed according to the above method, and then polymerizing ethylene and propylene. By changing the hydrogen concentration and dividing the copolymerization reaction into two stages in which the reaction ratio is in the range of 20/80 to 9515 weight ratio, the MW/MN in the high molecular weight range can be set to the desired value. .

Another preferred method is to use a catalyst system that provides a copolymer with a wide molecular weight distribution in the high molecular weight range. Many eroded catalyst systems are already known, but it is not known what kind of molecular weight distribution the copolymers obtained for each catalyst system have, so it cannot be determined for all catalyst systems. As a catalyst system that provides a wide molecular weight distribution in a relatively high molecular weight range, a titanium compound prepared by treating a titanium compound with a halide, especially a halodanized hydrocarbon, is used as the titanium component, or an oxygen-containing compound, especially an oxygen-containing compound, is used during polymerization. When a ketone compound is used as the organic acid ester, a copolymer with a wide molecular weight distribution in a high molecular weight range tends to be obtained, although the reason is not clear. In particular, as a catalyst system that provides a copolymer with a wide range of high molecular weights, an active titanium catalyst obtained by supporting titanium halide on a carrier prepared by treating magnesium halide with a halide hydrocarbon and an oxygen-containing compound, an organoaluminum compound, and an organic acid. Mention may be made of catalyst systems consisting of esters.

As mentioned above, when using a catalyst system that produces a copolymer with a wide molecular weight distribution in a relatively high molecular weight range,
There is no need to divide the process into two stages, and in each stage, polymerization is carried out at a constant hydrogen concentration in the gas phase and at a constant polymerization temperature. The composition of the present invention can also be obtained.

The composition of the present invention has excellent properties as a highly fluid, impact-resistant polypropylene for injection molding, such as high elongation at break of molded products, and is therefore of industrial value. The present invention will be further explained with reference to Examples below.

In Examples and Comparative Examples, physical properties are measured by the following method.

MF! (,j9/10m1n) ASTM D12
38 Tensile yield strength (kg/cm2) ASTM D
638-64T Elongation at break (H) ASTM D6
38-64T bending rigidity (kF2m2) ASTM
D747-63 Izot impact strength with notch) (k
g・cy'cm2) ASTM D256-56MFI
is 230℃, and other physical properties are 8 cm with an injection molding machine.
Injection sheets measuring 16 cm x 2 tan were prepared and measured at 23°C, and the impact strength was also measured at -10°C.

Example (1) Production of active titanium catalyst 1) 20 g of magnesium chloride, ethyl orthoacetate lπJ
, 1,2-dichloroethane 4m7! Activated titanium catalyst (a) obtained by repeating three times an operation of co-pulverizing titanium tetrachloride and then washing with n-hebutane.

II) A commercially available highly active titanium trichloride catalyst, TBN-05 (lot number) manufactured by Marubeni Solve U, was used as the catalyst! ! Well, use it.

Activated titanium catalyst (b).

(2) Production of block copolymer Polymerization conditions i) 250 kg of propylene is charged into a 1 m3 jacketed autoclave which has been thoroughly dried, purged with nitrogen, and further purged with propylene. On the other hand, n-
Henotan 2.51. Diethyl, aluminum, chloride 3.5 tnl 1. p -F Methyl ruylate 4-
A mixture of the activated titanium catalyst (a) 2.9 and 3 ml of triethylaluminum was introduced into the autoclave and polymerized at 75°C for 2 hours with a constant hydrogen concentration, and then the hydrogen concentration was decreased while lowering the internal temperature to 50°C. Then, add 50 ml of propylene, then add ethylene, maintain the ethylene concentration in the gas phase at 35 vol %, add triethylaluminum 1-, polymerize for 5 minutes, and then add until the ethylene concentration becomes 40 vol %. Another 1.5
After polymerization for a minute, the catalyst was immediately deactivated with ingropanol and the slurry was washed three times with propylene at 40°C to obtain polyzolopylene.

Polymerization conditions 11) n-
Polymerization was carried out at 70° C. for 2 hours at a total pressure of 10 kg/6N2-gauge using hebutane as a medium. At this time, polymerization was carried out in two stages with the hydrogen concentration kept constant or with the hydrogen concentration varied. After 2 hours, the temperature was lowered to 50°C, and the ethylene concentration in the gas phase was set to 30 vol% for 10 minutes, and then the ethylene concentration in the gas phase was reduced to 40 vol.
%, polymerization was carried out for 5 minutes. At this time, the ethylene concentration is 30yo
Polymerization at each stage of 1% and 40vo 1% was carried out with the hydrogen concentration constant or the hydrogen concentration was changed to ethylene concentration 3 Qvo
The concentration was changed at each stage of 1% and 40vo1% (the latter was 1/3 of the former concentration). After the polymerization reaction, the catalyst was deactivated with methanol and washed repeatedly with drained water, and the n-hebutane layer was filtered to obtain a copolymer powder. After drying the powder obtained in 1) and 11), a phenolic antioxidant (2/1000 weight ratio of the powder) and calcium stearate (1/1 (100 weight ratio) of the powder) were added and granulated, followed by injection. A molded sheet was made and its physical properties were measured.The results are shown in the table.

In addition, in Example 2 and Comparative Example 1, the powder of Example 1 was granulated using a peroxide removal agent that was used to granulate the powder at a ratio of 0.8/10,000 and 2.5/10,000 to the powder. The aliphatic peroxide Lupazol 101 (trade name, manufactured by Lucidor Yoshitomi) was used as the peroxide, and was degraded by heating at 250°C.

In Example 4, Example 3 was granulated by adding peroxide at a weight ratio of 1.2/10,000 to the powder. Example 3 was the same as Example 1 except that the hydrogen concentration was changed and the polymerization was carried out.
h5+ each

[Brief explanation of the drawing]

FIG. 1 is a drawing showing a molecular weight distribution curve and its division method, in which a shows a high molecular weight range, b shows an intermediate weight range, and C shows a low molecular weight reduction.

Claims (1)

[Claims] A polyzolopyrene resin with a melt flow index of 20 or more, in which the portion (4) soluble in white kerosene at 30°C is 5 to 20% by weight of the total, and the ethylene content in the core is 20 to 7.
03I is not soluble in white kerosene at 30℃ and is boiling.
The part (B) insoluble in n-hebutane accounts for 50 to 9 of the total
0 weight ft%, and the peak of the molecular weight distribution curve in which parts (A) and (B) are measured by Dal permeation chromatography, and the vertical axis is the elution amount and the horizontal axis is the natural logarithm of the molecular weight. When the high molecular weight region is approximated by a Gaussian distribution for the high molecular weight region, low molecular weight region, and intermediate weight region centered on the position of A highly fluid polyzolopyrene resin composition with high elongation at break, characterized by: